This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The lymphatic system consists of thin-walled vessels and lymph nodes that collect protein-rich fluid (i.e. lymph) and return it to the blood stream. Recent advances provided insight into the regulation and role of the lymphatics during embryogenesis and cancer metastasis, but there is little information on their development (lymphangiogenesis), maintenance, or destruction (lymphangiolysis) in healthy, adult tissues. The ovary should be an excellent organ for studying the physiology of the lymphatics, since the cyclic and temporary formation of gametogenic/endocrine tissues such as the corpus luteum (CL) is associated with remarkable changes in blood flow and vascular permeability. To date, there are no reports on the lymphatics in the primate CL. Therefore, studies are proposed to test the hypothesis that the lymphatic system exists in the primate CL and that CL development is associated with lymphangiogenesis. Using the rhesus monkey as a primate model, studies were designed: (a) To investigate the presence, localization, and dynamics of lymphatic vessels in the primate ovary, specifically in the CL throughout the luteal lifespan of the menstrual cycle;(b) To analyze the expression of novel lymphangiogenic factors, vascular endothelial growth factor (VEGF)-C and -D, and their receptor VEGFR-3 in the CL. This knowledge will contribute to our understanding of the structure-function of the primate CL, and should provide a solid rationale for further studies on the regulation and role of the lymphatic system in the primate ovary during the normal menstrual cycle and in ovarian disorders, such as ovarian hyperstimulation syndrome or ovarian cysts.